Each story had about 480MJ worth of energy. That's equivalent to about 1/10 of a ton of TNT. That's each story falling just one floor mind you. http://www.wolframalpha.com/input/?i=%281500000+tons+%2F+110...

For the North tower that's 120 floor equivalents as the 15 floors fell, about 12 tons of TNT.

For the entire tower that's 700 tons of TNT (assuming the mass of the tower is distributed evenly, which it isn't, but it's still a huge amount of energy).

What is that in relation to the speed of free fall of that floor? Is that roughly half? - i.e. in total free fall, you would expect that the floor would fall at 9.8 * 10^8 kgm^2/s^2?

Thanks!

Gravity is 9.8 m/s^2. Not 9.8 * 10^8!!! And the result is kg m^2/s^2 not m/s^2.

The result assumes a free fall at 1 g. I multiply it by g in order to accomplish that. (It's on earth, it can't really fall slower. If you want it to fall slower, the only thing it can do is fall, hit something and stop, then fall again - but that has 0 impact on the energy released! The energy released does not care if the building hit something and stopped momentarily in the processes.)

I know the result looks superficially like the units for gravitational acceleration but it's not, it's also multiplied by kg * m. i.e. I multiply gravity by mass and by how far it fell. The end result is the units for energy.

If you look up Joule http://en.wikipedia.org/wiki/Joule you'll see that it is defined that way.

There is a reason they push so hard to make sure you do the units correctly in Physics - you can gain a lot of insight into what you are calculating if you manipulate them properly.

So, in concluding...what would you say - based on your analysis here - about the assertion that this may have been caused by a 'controlled demolition'.

If you can just summarize your findings here, into a succinct statement that would be greatly appreciated :)

E.g. "The theories don't make sense, because as we saw here....X, Y & Z." or "The theories DO make sense, because Z, Y & X".

Where did you get the 15000000 tons figure from.

Also..what relation does 480MJ of energy have on the rate at which the building would have collapsed?

Are you debunking the theory that it was explosives, or supporting it?

I'm saying that there is more energy in simply the tower falling than there would be in any explosive. So it would not fall any faster with an explosive - there already is much more energy there than needed.

How are you sure that they wouldn't be able to use "more than enough" explosives though? 1/10 of a ton of TNT on each floor, sounds like a lot...but doesn't sound like an enormous amount.

Can you put that in terms that a layman may understand?

Thanks.

P.S. I would love more details, so that I can properly refute these claims based on physics and facts - than just based on philosophy and intuition.

1/10 of a ton (200 pounds) of explosives is a staggering amount in comparison. The energy involved in the building falling down swamps the explosives by such a large degree that you couldn't even tell the difference.

Remember that the fire did the same thing that a controlled explosion would do: Weaken the central support. The fire by softening the metal, an explosion by cutting it.

A controlled demolition does not actually explode the building, all it does is weaken the support, and gravity does the rest.